Five days before major primaries in Florida and Ohio, the Republican debate took on a more measured tone after the nasty insults of previous debates. Front-runner Donald Trump even remarked, "I can't believe how civil it's been up here."

There was also an attempt to discuss more substantive issues such as Social Security, ISIS, trade and education, which the candidates took as opportunities to criticize the Obama administration. Texas Senator Ted Cruz and Florida Senator Marco Rubio also made the most of the issues to present themselves as the best alternative to Trump.

Social Security

In a discussion on Social Security, in a state with over 3 million retirees, Cruz and Rubio both said they would raise the retirement age for younger workers to help stabilize the system and stave off the alleged insolvency Republicans claim is coming for the benefit program.

Trump, in contrast, said he'd do "everything within my power not to touch Social Security, to leave it the way it is."

Cruz argued the system was "careening toward insolvency" and that it would be irresponsible not to address the problem. Rubio said Trump's plan to save the system by eliminating all fraud and waste wouldn't work as the "the numbers don't add up."

When asked about Common Core standards, candidates portrayed them as centralized and disseminated from the top-down. Trump said he didn't want education policy set through Washington and Cruz called Common Core “a disaster.”

"I intend to work to abolish the federal Department of Education and send education back to the states and back to the local governments," Cruz said.

ISIS

When asked about comments made by General Lloyd Austin III, the head of US Central Command, favoring troops on the ground to defeat Islamic State (IS, formerly ISIS) in Syria and Iraq, all presidential candidates aligned with the military view, one antithetical to the Obama administration's strategy against IS.

"We really have no choice, we have to knock out ISIS,” Trump said. “I would listen to the generals, but I’m hearing numbers of 20,000 to 30,000.”

Marco Rubio offered a more substantive response, that in order to defeat IS, it must be denied room to operate.

"This is how ISIS, or any radical group for that matter, can grow,” Rubio said. “It's how Al-Qaeda was able to carry out 9/11, is that the Taliban gave them operating space in Afghanistan. Today that operating space has been largely based in Iraq and Syria."

"They do need to be defeated on the ground by a ground force made primarily of Sunni Arabs themselves,” Rubio continued. “This is a radical Sunni movement. They can only be defeated if they are driven out, and the territories held by Sunni Arabs, but it will require a significant number of American special operators in combination with an increase in airstrikes."

Trade

Trump said the he differed from typical Republicans on just one issue: his stance on trade. He said the US had had "horrible negotiators, horrible trade deals." He argued the US needed to renegotiate its trade deals, threatening to slap import tariffs on countries "unless they behave."

Rival Ted Cruz said that such a move under Trump's plan would only boost the prices of consumer goods.

"We've got to get beyond the rhetoric of China, bad, and get to, how do you solve the problem?" Cruz said.

Trump spun that around by saying the US can always "build new factories and make more products here," a remark met with loud applause and cheers from the audience at Miami University.

Trump is about one-third of the way to the 1,237 delegates he needs to win the nomination. He’s the favorite to win Florida’s winner-take-all primary on Tuesday where 99 delegate votes are at stake. He is battling Ohio Governor John Kasich in a close race for all 66 of Ohio’s delegates that are also up for grabs on that day.